Trastuzumab, a humanized monoclonal antibody, significantly improves outcomes in HER2-neu positive breast cancer. The incidence of cardiotoxicity with trastuzumab is approximately 8 to 10%. This study was designed to analyze the incidence and risk factors associated with trastuzumab-related cardiotoxicity in real-world settings. This was a single institutional retrospective analysis of the incidence of trastuzumab-related cardiotoxicity in nonmetastatic HER2-positive, invasive breast cancer from January 2013 to December 2018. Trastuzumab-related cardiotoxicity was defined as symptomatic heart failure or asymptomatic decline in left ventricular ejection fraction (LVEF) by more than or equal to 10% or LVEF less than 50%. Risk factors analyzed were higher body mass index (≥30 kg/m2), history of diabetes, hypertension, cardiac disease, left-sided radiotherapy (RT), and prior exposure to anthracyclines. Out of the 246 patients diagnosed with early stage HER2-positive breast cancer, 117 (47.5%) received trastuzumab and constituted the study population. Trastuzumab-related cardiotoxicity was seen in a total of 16 (13.6%) patients. Eleven (9.4%) patients had an asymptomatic decline, while symptomatic LV dysfunction was seen in five (4.2%) patients. The median baseline ejection fraction was 65% (range, 56–72). The median time to development of cardiotoxicity was 18.5 weeks (range, 3–52) and the median trastuzumab cycle for cardiotoxicity was 6 (range, 2–16). Ten (62.5%) patients were rechallenged with trastuzumab following which one patient developed an asymptomatic decline in ejection fraction and one patient developed symptomatic heart failure. Cardiac-related mortality was seen in one (0.85%) patient. Left-sided RT to chest (p = 0.012) and presence of more than or equal to two risk factors (p = 0.01) had significant impact on incidence of cardiotoxicity. Approximately 14% developed trastuzumab-related cardiotoxicity that was slightly higher compared with that seen in clinical trials. Left-sided RT to chest and presence of two or more risk factors had significant impact on development of cardiotoxicity.

Article published online:
27 September 2023

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